Tunnel heading describes the step-by-step creation of underground cavities with typically small to medium cross-sections. It is used in classic adit construction, in tunnel construction for cross passages and escape routes, in utility and cable works, and in mining. Rock or concrete is removed in controlled work cycles; the tunnel face is secured, the cross-section is profiled, and the lining is installed. In this technical environment, hydraulic tools are often used that operate with low vibration levels and deliver precise results in confined conditions. These include, in Darda GmbH’s portfolio in particular, rock and concrete splitters, concrete demolition shears, hydraulic power packs, combination shears, rock wedge splitters, Multi Cutters, steel shears, and tank cutters.
Definition: What is meant by tunnel heading
Tunnel heading refers to the creation of an underground cavity (adit) by stepwise excavation at the tunnel face followed by immediate support and lining. Typical features are smaller to medium cross-sections, closed boundary conditions, and varying geology. Depending on the ground, the heading proceeds mechanically (excavator with suitable excavator attachments, partial-face cutting, drilling and splitting), by drilling and blasting, or using special methods. In contrast to machine full-face excavation of entire tunnel cross-sections (e.g., with tunnel boring machines), tunnel heading is more flexible, allows adaptations to the geology, and is frequently used for exploration headings, cable and utility headings, cross passages, connection and escape headings, as well as access structures.
Methods and construction sequence in heading works
The construction sequence is divided into short advance cycles: excavation at the tunnel face, trimming and profiling, support and lining, material haulage, and construction logistics. The choice of method depends on rock mass, hydrogeology, cross-section, surrounding conditions, and protected assets at the surface.
Excavation techniques
- Mechanical heading: Loosening by excavator with suitable excavator attachments, partial-face cutting, drilling, wedging, and hydraulic splitting. Here, rock and concrete splitters and rock wedge splitters from Darda GmbH are used to open rock in a controlled manner without generating relevant vibrations.
- Drilling and blasting: Classic cycle of drill plan, charging, blasting, ventilation, and mucking. In sensitive areas, explosive energy is reduced and combined with splitting technology to minimize vibrations.
- Selective removal: Trimming, profile correction, and exposing structures with concrete demolition shears, Multi Cutters, or combination shears—especially when dismantling existing underground structures.
Support and lining
- Initial support: Shotcrete, anchors, lattice girder beams, and spiling umbrellas to stabilize the rock mass immediately after each round.
- Final lining: Shotcrete shell, masonry lining, or segment ring–like solutions for special requirements; profile accuracy is checked regularly.
- Construction-phase profiling: concrete demolition shears and Multi Cutters from Darda GmbH are used to remove reinforced concrete in a controlled way, release built-in components, and expose reinforcement.
Material haulage logistics
Depending on heading length and gradient, haulage is via haulage vehicles, conveyor belts, or rails. Hydraulic power packs from Darda GmbH supply the attachments and handheld tools with the required energy, even in areas with limited power supply or restrictive emission requirements.
Applications of tunnel heading and links to tools
Tunnel heading serves as a precise and adaptable method in numerous disciplines. Tool selection is always project-specific.
- Rock excavation and tunnel construction: Controlled removal of hard rock with splitters; rework of edges, niches, and profiles with Multi Cutters. Under delicate tunnel face conditions, splitting techniques can complement the drilling and blasting sequence.
- Concrete demolition and special demolition: Removal of reinforcements, transverse openings, and temporary construction states with concrete demolition shears, steel shears, and combination shears; exposing and cutting reinforcement.
- Strip-out and cutting: In existing underground structures, embedded parts, steel sections, pipelines, and tanks are cut with steel shears, combination shears, or tank cutters—especially during conversions and connection works.
- Natural stone extraction: Splitting and loosening of rock beds in underground extraction with rock wedge splitters; low vibration levels protect sensitive surroundings.
- Special applications: Work in hospital environments, heritage areas, or densely built urban settings requires low-emission, low-vibration methods. Hydraulic splitters and concrete demolition shears help meet the requirements.
Geotechnics, investigation, and planning
Robust planning is based on ground investigation, laboratory testing, hydrogeological analyses, and forecasts of rock mass behavior. From this derive the heading method, round length, support concept, water control, and emergency strategies.
Influencing factors for method selection
- Strength, bedding, and jointing of the rock mass
- Water inflows, gas occurrences, and rock pressure
- Overburden, proximity to structures, and permissible vibrations
- Cross-section geometry, radii of curvature, and accessibility
- Occupational safety, escape routes, ventilation, and logistics
Where strict vibration and noise limits apply, mechanical removal, rock and concrete splitters and concrete demolition shears are preferred to loosen the tunnel face in a controlled manner and ensure profile accuracy.
Safety and health protection in tunnel heading
Safety takes priority. Underground works require regulated workflows, training, personal protective equipment, effective ventilation, fire protection and explosion protection, and orderly material handling. The handling of explosives, the cutting of steel components, and hydraulic splitting must be planned and supervised in accordance with applicable regulations. Statements here are generally of a general nature; project-specific requirements of the authorities and the relevant codes are decisive.
Emissions and vibrations
Dust, vibrations, and noise must be minimized. Hydraulic splitting technology operates with low vibration levels, which reduces settlement and impacts on structures. Concrete demolition shears and steel shears enable controlled separation of reinforced components, lines, or profiles with low emissions.
Materials, lining types, and finishing
Initial and final linings range from shotcrete with anchors to masonry linings. During adjustments, temporary supports are removed, edges are re-profiled, and embedded components are relocated.
- Profile correction: Trimming with splitters, fine finishing with Multi Cutters.
- Dismantling of temporary elements: Removing spiles, lattice girder beams, and auxiliary structures with concrete demolition shears and steel shears.
- Steel and tank works: Cutting steel beams or underground tanks with tank cutters within defined safety concepts.
Construction logistics and power supply
In headings, cross-section and airflow limit the choice of equipment. Compact hydraulic power packs from Darda GmbH supply splitters, shears, and cutters via hose lines. Low waste heat, demand-based power, and safe quick couplings are important. Transport routes, intermediate storage, and maintenance areas must be planned so that heading and support proceed without interfering with each other.
Typical challenges and technical solutions
- Blocky or anisotropic rock mass: Preferably drilling and splitting along existing joints; reduced explosive charges to preserve the tunnel face.
- Water inflows: Pre-injection, drainage, and secured material haulage; corrosion-protected tools and regular maintenance.
- Reinforced concrete in existing structures: Selective deconstruction with concrete demolition shears, exposing reinforcement, then cutting with steel shears.
- Proximity to sensitive structures: Low-vibration sequences, short rounds, splitters instead of heavy percussion hammers.
- Confined geometries: Compact handheld tools and modular power packs to ensure reach and maneuverability.
Application examples in the project workflow
Exploration and access headings
Small cross-sections are advanced for geology and groundwater investigation. Mechanical removal and splitting limit vibrations; profile correction is performed with Multi Cutters.
Cross passages and escape tunnels
Precise breakthroughs are required in existing tunnel bores. Concrete demolition shears create controlled openings; steel shears cut reinforcement and embedded components.
Rehabilitation and special demolition
When removing old linings, concrete is released in sections, steel is cut, and the profile is re-established. rock and concrete splitters minimize impacts on the surroundings.
Sustainability, resource efficiency, and quality
Resource conservation starts with method selection: lower vibrations, minimized energy input, and clean, source-separated handling of muck. Hydraulic tools with demand-based power reduce emissions. Quality assurance includes measurements of profile accuracy, documentation of support elements, visual inspections of the tunnel face, and regular functional tests of the equipment.
Terms and classification in the context of tunnel construction
Tunnel heading lies between classic adit construction and large cross-section tunnel excavation. Adits serve as exploration, service, cable, or water headings, as cross passages between bores, and as access to caverns. Shafts connect the surface and headings; cross passages create transverse connections. In all cases, the principles of safe excavation, timely support, and profile-accurate execution apply—supported by suitable hydraulic tools such as concrete demolition shears and rock and concrete splitters from Darda GmbH.